SUPPORTED ELECTROCATALYST FOR ENHANCED ELECTROCHEMICAL AMMONIA PRODUCTION

Description

TECHNICAL FIELD

The present technology relates to ammonia production. More specifically, the present technology relates to nanoparticle based catalysts for electrochemical nitrogen reduction reactions (NRR) for producing ammonia.

BACKGROUND OF THE INVENTION

Ammonia is one of the most important chemicals in the world. Each year, roughly 200 million tons of ammonia are produced around the world, many of which can be involved in production of agricultural fertilizers for sustaining crop production and global food security. Ammonia can also be used by various industries, such as pharmaceuticals, defense/weapons, textiles, chemical synthesis, and petrochemicals to name a few. Ammonia may also play an important role in a potential hydrogen economy and may be a potential green fuel.

Conventional commercial ammonia production can involve a Haber Bosch process. In the Haber Bosch process, atmospheric nitrogen (N₂) can react with hydrogen (H₂) derived from steam reforming of natural gas in a presence of heterogeneous iron-based catalysts at high temperatures (e.g., 300-500° C.) and high pressures (e.g., 150-300 atm). The Haber Bosch process can be unsustainable and environmentally undesirable due to a massive carbon footprint as well as harsh conditions and a high input energy requirement. Approximately 1% of global energy supply and 3-5% of global natural gas supply can be consumed by the Haber Bosch process, while the Haber Bosch process can generate more than 300 million tons of carbon dioxide (1% of global emissions) each year. A development of an efficient, sustainable, and carbon neutral alternative to the Haber Bosch process is important for future ammonia production.

There is a need for improved systems and methods that can be used for ammonia production. These and other needs are addressed by the present technology.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present technology may include electrochemical cell systems for producing ammonia. The systems may include a working electrode submerged in an electrolyte. The working electrode may include an iron foam (IF) substrate. The working electrode may also include a plurality of iron vanadate (FeVO₄) nanoparticles deposited on the IF substrate.

In some embodiments, the plurality of FeVO₄ nanoparticles may be formed from a hydrothermal method. The plurality of FeVO₄ nanoparticles may be deposited on the IF substrate by drop casting in a nanoink solution. The electrolyte may be or include diatomic nitrogen (N₂). The electrolyte may be continuously fed diatomic nitrogen (N₂) during an ammonia producing process. The electrolyte may be or include sodium sulfate (Na₂SO₄). The systems may include a counter electrode configured to produce a drive current with the working electrode. The systems may include a reference electrode for measuring an electric potential associated with the working electrode. The counter electrode may be platinum. The reference electrode may be Ag/AgCl.

Embodiments of the present technology may encompass methods for producing ammonia. The methods may include depositing a plurality of iron vanadate (FeVO₄) nanoparticles on an iron foam (IF) substrate to form a working electrode of an electrochemical cell. The methods may include submerging the working electrode in an electrolyte. The methods may include applying a potential difference between the working electrode and a counter electrode to produce the ammonia.

In some embodiments, applying the potential difference may include applying the potential difference between the working electrode and the counter electrode so that the counter electrode is at a higher potential than the working electrode. Applying the potential difference may include applying the potential difference between the working electrode and the counter electrode so that the counter electrode may be less than 1 reversible hydrogen electrode Volt (V_RHE) higher than the working electrode. The methods may include forming the plurality of FeVO₄ nanoparticles from a hydrothermal method. Depositing the plurality of FeVO₄ nanoparticles on the IF substrate may include drop casting the plurality of FeVO₄ nanoparticles in a nanoink solution on the IF substrate. The electrolyte may be or include diatomic nitrogen (N₂). The methods may include continuously feeding the electrolyte diatomic nitrogen (N₂). The electrolyte may include sodium sulfate (Na₂SO₄). The methods may include producing a drive current between the working electrode and the counter electrode, and measuring the applied potential difference using a reference electrode. The counter electrode may be platinum. The reference electrode may be Ag/AgCl. Applying the potential difference may include applying the potential difference between the working electrode and the counter electrode to produce ammonia at an ammonia yield greater than

4 ⁢ μ ⁢ g h / mg .

Applying the potential difference may include applying the potential difference between the working electrode and the counter electrode to produce ammonia with a Faradaic Efficiency greater than 10%.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a working electrode for an electrochemical system according to certain aspects of the present disclosure.

FIG. 2 is a graph showing an X-Ray diffraction (XRD) pattern of iron vanadate nanoparticles (FeVO₄ NPs) according to certain aspects of the present disclosure.

FIGS. 3A and 3B are illustrations of exemplary scanning electron microscopy (SEM) images of FeVO₄ NPs according to certain aspects of the present disclosure.

FIGS. 4A, 4B, 4C, and 4D are illustrations of exemplary energy-dispersive X-ray spectroscopy (EDX) elemental analysis and corresponding elemental mappings of FeVO₄ NPs according to certain aspects of the present disclosure.

FIGS. 5A, 5B, and 5C are illustrations of exemplary transmission electron microscopy (TEM) results of FeVO₄ NPs according to certain aspects of the present disclosure.

FIGS. 6A, 6B, 6C, and 6D are illustrations of exemplary X-ray photoelectron spectroscopy (XPS) graphs of FeVO₄ NPs according to certain aspects of the present disclosure.

FIG. 7 is a schematic cross section view of an electrochemical system according to certain aspects of the present disclosure.

FIG. 8 is a flow chart of an exemplary process that can be implemented to produce ammonia with a catalyst of FeVO₄ NPs on iron foam according to some examples of the present disclosure.

FIGS. 9A, 9B, 9C, and 9D are illustrations of exemplary graphs that highlight a catalyst performance of FeVO₄ NPs on iron foam according to certain aspects of the present disclosure.

FIGS. 10A and 10B are illustrations of exemplary results of control and stability tests associated with FeVO₄ NPs on iron foam according to certain aspects of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

An electrochemical nitrogen reduction reaction (NRR) can be a supplemental or replacement approach to the Haber Bosch process for producing ammonia. Theoretically, an electrochemical reduction of N₂ to ammonia using heterogeneous catalysts at ambient conditions can be feasible if a suitable electric potential is applied. Compared to the Haber Bosch process, an NRR approach may not require extreme reaction conditions or high energy input. Also, the NRR approach can be coupled to solar or wind renewable energy sources for continuous operations.

Certain aspects and examples of the present disclosure relate to an NRR approach for producing ammonia involving a reactive catalyst of an iron foam with iron vanadate (FeVO₄) nanoparticles (NPs). Iron foam can be a light weight, porous, and highly conductive substrate. The iron foam substrate may provide an enhancement to charge transfer, substance diffusion, and availability of more active sites to an NRR process. Iron foam with FeVO₄ NPs (FeVO₄/IF) can be an efficient and reactive NRR catalyst due to a coupling and electronic interaction between the iron foam and the FeVO₄ NPs. FeVO₄/IF can include dual metal centers (Fe³⁺ and V⁵⁺). The dual metal centers can tune electronic properties of the reactive catalyst and enhance N₂ activation energy, leading to a high ammonia yield, a significant Faradaic Efficiency (FE), and good stability.

In the following description, various embodiments will be described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will also be apparent to one skilled in the art that the embodiments may be practiced without the specific details. Furthermore, well-known features may be omitted or simplified in order not to obscure the embodiment being described.

FIG. 1 is a schematic perspective view of a working electrode 100 for an electrochemical system according to certain aspects of the present disclosure. The schematic perspective view is not drawn to scale. The working electrode 100 can include a substrate 105 and nanoparticles 110. The substrate 105 can be an iron foam substrate. The nanoparticles 110 can be iron vanadate nanoparticles (FeVO₄ NPs). Although seven nanoparticles 110 are shown in FIG. 1, the working electrode 100 can include any number of nanoparticles 110 including, for instance, over a million nanoparticles 110 or over a billion nanoparticles 110.

The FeVO₄ NPs can be synthesized via a hydrothermal method. For example, 4.0 mmol (0.013 grams) of iron chloride (FeCl₃) can be dissolved in 20 milliliters (ml) of deionized water to form an orange solution. 4.0 mmol (0.0094 grams) of ammonium metavandate (NH₄VO₃) can be dissolved in another 20 ml of deionized water and stirred until a clear solution forms. The orange solution can be added to the clear solution under magnetic stirring to form a yellow turbid colloidal solution. The yellow turbid colloidal solution can be stirred for 30 minutes, sealed in an autoclave, and heated to a temperature between about 150° C. and about 180° C. for between about 3 and about 6 hours. The autoclave can be lined with Teflon. An obtained precipitate can be washed several times with deionized water and ethanol to remove residual impurities and dried to obtain the FeVO₄ NPs.

The FeVO₄ NPs can be formed on the substrate 105 by drop casting a nanoink that includes the FeVO₄ NPs onto the substrate 105. Prior to drop casting, the substrate 105, such as the iron foam substrate, can be cleaned by sonication in an acetone bath, an ethanol bath, and a deionized water bath for 15 minutes each. Sonication can be repeated several times to remove oxides or other impurities that may be present in or on the substrate 105. After drying the iron foam, 150 microliters of the nanoink can be drop cast onto the pre-cleaned substrate 105. A formulation of the nanoink can be optimized after a series of experiments. In embodiments, the nanoink may also include, but is not limited to, one or more solvents (e.g., water and/or ethanol) and one or more binders, such as Nafion™ solution (C₇HF₁₃O₅S·C₂F₄). After drop casting, the substrate 105 with FeVO₄ NPs can be dried overnight, such as in a vacuum, to produce the working electrode 100.

FIG. 2 is a graph 200 showing an X-Ray diffraction (XRD) pattern 202 of iron vanadate nanoparticles (FeVO₄ NPs) according to certain aspects of the present disclosure. As previously discussed, the FeVO₄ NPs can be fabricated using a facile hydrothermal synthesis, such as the process as described above. The XRD pattern 202 reveals peaks 205, 210, 215, and 220 that match a triclinic crystal structure. Peaks 205, 210, and 220 can be assigned to (120), (220), and (330) planes of FeVO₄, respectively.

FIGS. 3A and 3B are illustrations of exemplary SEM images 300, 302 of FeVO₄ NPs according to certain aspects of the present disclosure. As previously discussed, the FeVO₄ NPs can be fabricated using a facile hydrothermal synthesis, such as the process as described above. SEM image 302 has a greater magnification than SEM image 300. Both SEM images suggest a formation of monodisperse FeVO₄ NPs with distinct grain-like structures, relatively small size, and uniform morphology. Negligible agglomeration can be observed in the morphology, which can indicate good stability of the FeVO₄ NPs.

FIGS. 4A, 4B, 4C, and 4D are illustrations of exemplary energy-dispersive X-ray spectroscopy (EDX) elemental analysis and corresponding elemental mappings of FeVO₄ NPs according to certain aspects of the present disclosure. As previously discussed, the FeVO₄ NPs can be fabricated using a facile hydrothermal synthesis, such as the process as described above. The EDX elemental analysis of FIG. 4A confirms a presence of iron (Fe), vanadium (V), and oxygen (O). FIG. 4B, FIG. 4C, and FIG. 4D show elemental mapping for Fe, V, and O, respectively. The elemental mappings confirm that the elements are uniformly distributed within the FeVO₄ NPs.

FIGS. 5A, 5B, and 5C are illustrations of exemplary TEM results of FeVO₄ NPs according to certain aspects of the present disclosure. As previously discussed, the FeVO₄ NPs can be fabricated using a facile hydrothermal synthesis, such as the process as described above. FIG. 5A is a TEM image of the FeVO₄ NPs. FIG. 5B is a high-resolution transmission electron microscopy (HRTEM) image of the FeVO₄ NPs. FIG. 5C is a selected area electron diffraction image of the FeVO₄ NPs. The TEM results indicate that the FeVO₄ NPs exhibit a nanoparticle morphology.

FIGS. 6A, 6B, 6C, and 6D are illustrations of exemplary XPS graphs of FeVO₄ NPs according to certain aspects of the present disclosure. As previously discussed, the FeVO₄ NPs can be fabricated using a facile hydrothermal synthesis, such as the process as described above. FIG. 6A shows an XPS survey spectrum plot that confirms a presence of Fe, V, and O elements, in addition to an observed carbon 1s peak originating from adventitious carbon. FIG. 5B shows a high-resolution scan for an Fe 2p spectrum that reveals two distinct peaks in the Fe 2p region at 727 eV and 713 eV. The two distinct peaks can be assigned to Fe 2p_1/2 and Fe 2p_3/2, respectively, confirming a presence of an Fe³⁺ species in the FeVO₄ NPs. FIG. 5C shows a deconvoluted V 2p spectrum with two well resolved peaks at 532 eV and 529 eV corresponding to V⁵⁺2p_1/2 and V⁵⁺2p_3/2, respectively. Similarly, FIG. 5D shows an O 1s spectrum with twin peaks at 533 eV (labeled O1) and 535 eV (labeled O2) that can be linked to lattice oxygen and an adsorbed oxygen species, respectively.

FIG. 7 is a schematic cross section view of an electrochemical cell system 700 according to certain aspects of the present disclosure. The electrochemical cell system 700 can include an electrochemical cell 750 that is “gas-tight” with a three-electrode configuration. The electrochemical cell 750 can include an electrolyte 710, a working electrode 702, a counter electrode 706, and a reference electrode 704. Electric potentials within the electrochemical cell 750 can be monitored and measured with a potentiostat 712.

The working electrode 702 can be, for example, working electrode 100 from FIG. 1. The working electrode 702 can be formed from an iron foam substrate with deposited FeVO₄ NPs. Platinum, for example, can be used as the counter electrode 706. The reference electrode 704 can be a silver/silver chloride (Ag/AgCl) electrode. The Ag/AgCl electrode can include a metallic Ag wire coated with a thin layer of AgCl. The Ag wire can be coated physically by dipping the Ag wire in molten AgCl, chemically by electroplating the Ag wire in concentrated hydrochloric acid, or electrochemically by oxidizing Ag at an anode in a chloride solution. The electrolyte can be a nitrogen (N₂) saturated to 0.1 molarity in sodium sulfate (Na₂SO₄). In some examples, nitrogen gas can be continuously fed into the electrochemical cell 750 at a constant rate.

Electrochemical System Characterization

For quantifying production of ammonia using the electrochemical cell system 700, a salicylate indophenol blue method can be used. After each chronoamperometric test, a 2 mL aliquot of electrolyte can be removed from the electrochemical cell 750. 2 mL of 1 molarity sodium hydroxide solution containing 5 wt. % salicylic acid and 5 wt. % sodium tricitrate can be added to the aliquot. An additional 1 mL of 0.05 molarity sodium hypochlorite and 0.2 mL of 1 wt. % sodium nitroprusside solution can also be added. After an incubation of 1 hour at room temperature, absorbance measurements can be carried out with a UV-Vis spectrophotometer set at a wavelength of 655 nm. Absorbance peaks can be calibrated using a standard NH₄Cl solution with series of concentrations in 0.1 molarity Na₂SO₄. All potentials relative to the reference electrode 704 can be converted to a reversible hydrogen electrode voltage V_RHE according to an equation known as the Nernst equation, as shown in Equation (1).

E R ⁢ H ⁢ E = E A ⁢ g / A ⁢ g ⁢ C ⁢ l + 0.059 pH + 0.197 V ( 1 )

Ammonia yield can be calculated according to Equation (2).

Ammonia ⁢ Yield ⁢ ( μgh - 1 ⁢ mg - 1 ) = C N ⁢ H 3 × V m × t ( 2 )

Faradaic Efficiency can be determined using Equation (3).

Faradaic ⁢ Efficiency ⁢ ( % ) = 3 × F × C N ⁢ H 3 × V M W × Q × 1 ⁢ 0 ⁢ 0 ( 3 )

In Equations (1), (2), and (3), C_NH3 is a measured ammonia concentration, V is a volume of electrolyte, m is a mass loading of catalyst on iron foam, t is electrolysis time, F is Faraday's constant, M_W is a molecular weight, which is roughly 17 g/mol for ammonia, and Q is a quantity of applied charge.

FIG. 8 is a flow chart of an exemplary process that can be implemented to produce ammonia with a catalyst of FeVO₄ NPs on iron foam according to some examples of the present disclosure. FIG. 8 may describe operations previously discussed with respect to the components in FIG. 7. Accordingly, any of the following operations of method 800 may include features or characteristics of electrochemical cell system 700 previously described with regard to FIG. 3.

Operation 802 of method 800 may include depositing a plurality of FeVO₄ NPs on an IF substrate to form a working electrode of an electrochemical system. The plurality of FeVO₄ nanoparticles can be formed from a hydrothermal method, such as the process previously described. A nanoink solution can be formed that includes FeVO₄ NPs, which can be deposited on the IF substrate by drop casting the nanoink solution. The IF substrate can be cleaned prior to deposition of the FeVO₄ NPs. After drop casting, the working electrode can be dried overnight in a vacuum.

Operation 804 of method 800 can include submerging the working electrode in an electrolyte. The electrolyte can include diatomic nitrogen (N₂). In some examples, the electrolyte can be or include a sodium-containing electrolyte, such as sodium sulfate (Na₂SO₄). For example, the electrolyte may be 0.1 M sodium sulfate (Na₂SO₄) saturated with N₂. A counter electrode and a reference electrode can also be submerged in the electrode. In some examples, the counter electrode is platinum, and the reference electrode is Ag/AgCl. The FeVO₄ NPs/IF working electrode can act as a catalyst for an ammonia producing electrolysis process.

Operation 806 of method 800 can include applying a potential difference between the working electrode and a counter electrode to produce ammonia. The potential difference can be in terms of or relative to a reversible hydrogen electrode voltage V_RHE. The potential difference can be applied so that the counter electrode is at a higher potential than the working electrode. For example, the counter electrode can be less than 1 V_RHE higher than the working electrode. The applied potential difference can be measured and monitored relative to the reference electrode. The applied potential difference can create a drive current between the working electrode and the counter electrode. The applied potential difference can be described relative to the working electrode and can be a negative potential difference.

Applying the potential difference can cause ammonia to form in the electrolyte. In some examples, the electrolyte can be continuously fed N₂ during ammonia production. The ammonia can form under ambient conditions, such as under room temperature and normal atmospheric pressures. The FeVO₄ NPs/IF working electrode can act as a catalyst for the production of ammonia. The FeVO₄/IF catalyst can help achieve an ammonia yield of greater than or about

4 ⁢ μg h / mg ,

greater than or about

5 ⁢ μg h / mg ,

greater than or about

6 ⁢ μg h / mg ,

greater than or about

7 ⁢ μ ⁢ g h / mg ,

greater than or about

8 ⁢ μ ⁢ g h / mg ,

greater man or about

9 ⁢ μ ⁢ g h / mg ,

greater than or about

9.3 μ ⁢ g h / mg ,

or more. The FEVO₄/IF catalyst can help achieve a Faradaic Efficiency of greater than or about 10%, greater than or about 15%, greater than or about 20%, greater than or about 25%, greater than or about 30%, or greater than or about 31.3%. For example, the FeVO₄/IF catalyst can achieve an ammonia yield of

9.3 μ ⁢ g h / mg

at −0.3 V_RHE and a Faradaic Efficiency of 31.3% at −0.2 V_RHE.

The NRR performance of the FeVO₄/IF catalyst can be attributed to a number of factors. The factors can include a self-supporting structure of the FeVO₄/IF working electrode. The IF may be a porous, self-supporting material that can offer support and dispersion for FeVO₄ NPs, creating numerous active sites and a robust structural framework. The factors can also include an enhanced conductivity. The 3D IF can enhance conductivity of catalyst material. The IF can permit the electrolyte to penetrate the catalyst material and can shorten electron transfer pathways. The factors can further include a bimetallic dual interface and a synergistic effect. A presence in the catalyst of a bimetallic two-phase interface (involving both FeV and FeFe nearest neighbor interactions) can generate dual metallic active sites. Dual metallic active sites may improve a local charge density, modulate electronic states of the catalyst, and facilitate enhanced N₂ adsorption and activation.

The order of the operations of method 800 presented in the examples above can be varied. For example, operations can be re-ordered, combined, and/or broken into sub-operations. Certain operations of method 800 may also be performed in parallel.

Examples

FIGS. 9A, 9B, 9C, and 9D are illustrations of exemplary graphs that highlight a catalyst performance of FeVO₄ NPs on iron foam according to certain aspects of the present disclosure. FIG. 9A shows current density plots for linear sweep voltammetry (LSV) measurements for an electrochemical system such as electrochemical cell system 700 from FIG. 7. The electrochemical system included an iron foam substrate with deposited FeVO₄ NPs as a working electrode/catalyst. Platinum was used as the counter electrode. The reference electrode was a silver/silver chloride (Ag/AgCl) electrode. The LSV measurements were conducted in both an N₂ saturated 0.1 M Na₂SO₄ electrolyte and an argon saturated 0.1 M Na₂SO₄ electrolyte. NRR activity was assessed within a range of 0 to −1 V_RHE. To suppress a competitive hydrogen evolution reaction (HER), all electrochemical measurements were conducted at low potentials in the neutral sodium sulfate electrolyte. Within the range of measured potentials, a higher current density was observed in the N₂ saturated electrolyte than in the argon saturated electrolyte. The higher current density in the N₂ saturated electrolyte a reduction of N₂ enhanced by the FeVO₄/IF catalyst.

Chronoamperometry tests were conducted at three different voltages (−0.2 V_RHE, −0.3 V_RHE, and −0.4 V_RHE) for 2 hours using the N₂ saturated 0.1 M Na₂SO₄ electrolyte under a continuous flow of high purity nitrogen gas. FIG. 9B shows plots of current density versus time for the three different voltages. For each of the different voltages, samples of the electrolyte were collected and analyzed using the indophenol blue method. FIG. 9C shows absorbance versus wavelength plots for the collected samples. Peaks were observed at around 655 nm. FIG. 9D summarizes results for Faradaic Efficiency and ammonia yield, which were calculated according to Equations (2) and (3) above, respectively.

As previously discussed, the FeVO₄/IF catalyst can help achieve an ammonia yield of greater than or about

4 ⁢ μ ⁢ g h / mg ,

greater than or about

5 ⁢ μ ⁢ g h / mg ,

greater than or about

6 ⁢ μ ⁢ g h / mg ,

greater than or about

7 ⁢ μ ⁢ g h / mg ,

greater than or about

8 ⁢ μ ⁢ g h / mg ,

greater than or about

9 ⁢ μ ⁢ g h / mg ,

greater than or about

9.3 μ ⁢ g h / mg ,

or more. The FeVO₄/IF catalyst can help achieve a Faradaic Efficiency of greater than or about 10%, greater than or about 15%, greater than or about 20%, greater than or about 25%, greater than or about 30%, greater than or about 31.3%, or more. For example, the FeVO₄/IF catalyst can achieve an ammonia yield of

9.3 μ ⁢ g h / mg

at −0.3 V_RHE and a Faradaic Efficiency of 31.3% at −0.2 V_RHE. Beyond −0.4 V_RHE, both ammonia yield and Faradaic Efficiency may decrease, and current density may increase. The reduction in ammonia yield and Faradaic Efficiency may be due to adsorption of hydrogen on a catalyst surface. The hydrogen adsorption may drive a competitive hydrogen evolution reaction and hinder both adsorption and reduction of N₂ on the catalyst surface.

FIGS. 10A and 10B are illustrations of exemplary results of control and stability tests associated with a catalyst of FeVO₄ NPs on iron foam according to certain aspects of the present disclosure. A series of standard control experiments were carried out under different conditions. The different conditions included electrolysis in argon saturated 0.1 M Na₂SO₄ electrolyte, in N₂ saturated electrolyte but with no applied potential, and in N₂ saturated electrolyte but with a bare iron foam (no FeVO₄ NPs) working electrode. Results are summarized in FIG. 10A. Negligible amounts of ammonia were detected in the three control experiments. The negligible amounts demonstrate that detected ammonia originated from the NRR process involving the FeVO₄/IF catalyst and preclude possible interference from auxiliary ammonia sources such as feed gas, glassware, and atmosphere.

To evaluate a stability of the NRR process involving the FeVO₄/IF catalyst, a prolonged electrochemical stability test was conducted by running continuous electrolysis for 10 hours. Results of the electrochemical stability test are shown in FIG. 10B, which shows current density as a function of time. The current density was fairly steady with time with no observed fluctuations or current decay. The steady current density suggests that the FeVO₄/IF electrocatalyst possesses stability and operational robustness.

While the present subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, it should be understood that the present disclosure has been presented for purposes of example rather than limitation, and does not preclude inclusion of such modifications, variations, and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art. Indeed, the methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions, and changes in the form of the methods and systems described herein may be made without departing from the spirit of the present disclosure. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the present disclosure.

Conditional language used herein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain examples include, while other examples do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more examples or that one or more examples necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular example.

Disjunctive language such as the phrase “at least one of X, Y, or Z,” unless specifically stated otherwise, is otherwise understood within the context as used in general to present that an item, term, etc., may be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, such disjunctive language is not generally intended to, and should not, imply that certain examples require at least one of X, at least one of Y, or at least one of Z to each be present.

Use herein of the word “or” is intended to cover inclusive and exclusive OR conditions. In other words, A or B or C includes any or all of the following alternative combinations as appropriate for a particular usage: A alone; B alone; C alone; A and B only; A and C only; B and C only; and all three of A and B and C.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the disclosed examples (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. The use of “adapted to” or “configured to” herein is meant as open and inclusive language that does not foreclose devices adapted to or configured to perform additional tasks or steps. The term “connected” is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. Additionally, the use of “based on” is meant to be open and inclusive, in that a process, step, calculation, or other action “based on” one or more recited conditions or values may, in practice, be based on additional conditions or values beyond those recited. Similarly, the use of “based at least in part on” is meant to be open and inclusive, in that a process, step, calculation, or other action “based at least in part on” one or more recited conditions or values may, in practice, be based on additional conditions or values beyond those recited. Headings, lists, and numbering included herein are for ease of explanation only and are not meant to be limiting.

The various features and processes described above may be used independently of one another or may be combined in various ways. All possible combinations and sub-combinations are intended to fall within the scope of the present disclosure. In addition, certain method or process blocks may be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence, and the blocks or states relating thereto can be performed in other sequences that are appropriate. For example, described blocks or states may be performed in an order other than that specifically disclosed, or multiple blocks or states may be combined in a single block or state. The example blocks or states may be performed in serial, in parallel, or in some other manner. Blocks or states may be added to or removed from the disclosed examples. Similarly, the example systems and components described herein may be configured differently than described. For example, elements may be added to, removed from, or rearranged compared to the disclosed examples.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.